steinmayer



Oct. 26, 1943. A. e. STEINMAQYER FUSE 2 Sheets-Sheet 1 Original Filed May 14, 1931 INVENTOR g //rkr fJ/flzmagwr We ATTORNEY Reissued Oct-26, 1943 r 1 Re. 22,387

v FUSE I Alwin G. Steinmayer, Shorewood, Wis, assignor to Line Material Company,

South Milwaukee,

Wis., a corporationpf Delaware Original No. 1,952,635, dated March 27, 1934, Se-

rial No. 537,267, May 14, 1931.

Reissue No.

22,092, dated-May 5, 1942, Serial No. 434,023, March 9, 1942. This application for reissue June 4, 1943, Serial No. 489,721

25 Claims. (01. 200-127) This invention relates to fuses and is particularly directed to an expulsion type of fuse'structure and fuse link therefor.

One of the many difficulties involved in the use of expulsion type fuses is due to the fact that thesefuses are often called upon to interrupt currents which are not very large. For instance, in farm line service the load is usually small and is often a non-inductive load. Under these conditions the usual types of expulsion fuses do not give entirely satisfactory results, for frequently the current is only sufficient to rupture a small portion of the fuse without causing complete expulsion, thus causing subsequent leakage and carbonization which often results in complete destruction of the fuse structure. In addition, these leaks cause radio interference.

While this invention is not to be construed as limited to low capacity expulsion fuses, it nevertheless is eminently suitable for such use and overcomes the defects noted above.

Objects of this invention are to provide an expulsion fuse which will insure complete and adequate-separation of the severed portions of the fuse, even if the fuse is only slowly melted; which will have in addition an expulsion action thus securing quick clearing of the fuse for large overloads; which insures clearing of the fuse for both small and large overloads, and renders this clearing of the fuse, or opening of the circuit, certain and sure under all conditions of operation.-

Further objects are to provide a fuse which closely conforms in dimensions to the standard type of expulsion fuses; which does not require an elaborate and expensive construction; which secures both the advantages of an expulsion action and also a spring action in insuring separation of the severed portions of the fuse; and in which the major parts, with the exception of the fusible section, are uninjured during operation,

and may be used over and over.

Further objects are to provide an expulsion type' of fuse which, in certain forms, is so constructed that a telltale or visible indication is given upon blowing of the fuse; in which a portion projects'downwardly from the lower end of the fuse tube; and in which the projecting portion, even if presenting conducting portions, is

restrained from passing completely from the fuse tube and dangling therefrom in a dangerous manner, and which, therefore, prevents danger tothe linemen and avoids the danger of short circuits or connecting with adjacent live wires or grounded parts.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a view, partly in section, of one form of the invention.

Figure 2" is a fragmentary view showing the position'of the parts after the fuse has blown.

Figure 3 is an enlarged detail of the upper portion of the link.

Figure 4 is a plan' view of the structure shown in Figure 3, with parts broken away.

Figure 5 is a modified form of attaching means for the upper end of the fuse link.

Figure 6 is a somewhat diagrammatic view showing how the upper end of the fuse link may be cut to cooperate with the type of fastening means shown in Figure 5.

Figure 7 is a view, partly in section,'showing a" modified form of fuse.

Figure 8 is a sectional view showing a still further. form of fuse.

Referring to the drawings, particularly Figures 1 to 4, itwill be seen that the expulsion fuse comprises-a fuse cartridge of insulating material which may comprise the insulating tube I, or which may be formed'of a plurality of tubes in accordance with any of the standard constructions. This phase of the fuse construction forms no portion of the invention, and for the sake of clearness a single tube has been shown.

The expulsion fuse is provided with an upper contact 2 and a lower contact 3. The upper contact may consist of a sleeve threaded upon the upper end of the tube and is itself provided with a reduced externally threaded upper end 4. A

metallic cap 5 is screwed upon this reduced end and serves to clamp the upper end of the fuse link in place. The lower contact surrounds the tube and is locked theretoin any suitable man ner. It is provided witha pair of spaced ears 5 between which the lower end of the fuse link is passed. A threaded, knurled thumb screw 1 is in threaded engagement with the ears 6, and serves lapping ribbons soldered together by a low melting point solder. The ribbons are in reality high resistance members, and the relative proportion of the cross section is such that under small over I loads the low melting point solder is fused, where-.

as under high overloads it is frequently the case that the major portion of the ribbons themselves are fused. At least under the latter condition an expulsion action takes place. Somewhat of an expulsion action takes place even under small overloads. However. it frequently happens that under 'verysnialli overloads, the full benefit of the expulsion "action is not secured. This defect,

however, is cured and eliminated by the structure the fusible section and forms a part of the fuse link. i a I The, enlarged upper portionof the fus link is preferably provided with an upper reversely folded portion II, which is clamped between the two plates [2 of an upper button or contact clip, the upper and lower portions of the cliptbeing .joined, as shown in Figure 4, and the'lower portion being apertured-to permit the passage therethrough of the upper end I of the portion particularly Figures 3 and 4.

The lower portion of the fusible section is joined to a relatively rigid section l3 which may consist of a relatively rigid wire, as indicated in Figures 1, 2 and 3. This wire may be attached to the hereinafter described, which is associated with 9', see a lower end of the fusible section in any suitable manner, as by means of the small screw ll. Any other mode of attachment may,of course, be used if it is found preferable. However, the use of the screw is desirable to permit ready substitution of new fusible sections, as it seldom occurs that any other portion of the fuse is damaged when rupture Occurs. I l

The wire I 3 or relatively rigid section, lselongated, and preferably at a point intermediate its end a helicai'spring I5 is attached. This helical spring is attached at its lower end to a. relatively strong, flexible copper leader l8, which is clamped by means of the screw I to the lower contact 3.

The ends of the rod l3 and the leader ii are joined by means of a very flexible copper leader l1 located preferably within the helical spring l5.

' Electrically, the leaders I 'l and I6 constitute the conducting means for carrying the currentfrom the rod I! to the lower contact 3, thereby preventing heating of the spring due to the passage of the current.

In view of the fact that these fuses are frequently used on farm lines and similarlocations where the load is relatively small and is usually v of a non-inductive nature, it is frequently the case that the overload is only of small value.- Even under these conditions complete and wide separation of the severed portions of the fusible section is obtained by the construction. described. Forexample, when the fuse blows, the spring fuse structure. However, this invention wholly avoids such defect. L

An additional advantage secured by thisinvention is that of a telltale action which indicates.

clearly when the fuse has blown. For example,

Figure 2 shows the position of the parts after blowing of the fuse,-and it will be seen that the rod or rigid member I: is projected downwardly and extends outwardly below the lower open end of the tube l, thus acting as-a telltale. It is prevented from passing completely from the tubeby means of the leader Iii. A comparison of Figures 1 1 and 2 will show the action of the fuse very clearly.

The partial retention of the rod or rigid mem ber l3 within the tubev is very desirable. Consider on the other hand, what would happen if the spring werenot strengthened, or held or guided by the rod I3; It would be projected outwardly from the tube and would dangle loosely from the lower portion of thestructure. relative flexibility, it might readily be blown into other live portions of adjacent structures, or againsta grounded section, or it might inadvertently contact with a lineman undertaking to renew the fuse. However, by means of the construction illustrated the complete expulsion of the spring and adjacent partsis prevented.

It is to be noted from Figures 5 and 6 that the upper end 9 of the fusible section is preferably provided with a slot or opening I8. The purpose of this construction is to allow acustomer to cut the upper end ,of the fusible section 011, as shown in dotted lines in Figure 6, and to thereafter slip the resulting prongs of the fusible section on op- D site sides of a screw I 9 secured to a contact button 20, or to. any other support as th case may be.v In'other words,..this type'of construc 'tion of the fusible section permits its use with at least two different types of upper attaching means. i

" Referring to Figure 7 where a modified form of the invention is disclosed, it will be seen that the same general inventive idea has been follgwed. The fusible section 2| may be of the same general 'type as that previously described and is locked to the upper contact 2 in any suitable manner, for instance by means of the cap]. The lower end of the fusible section is attached to the upper end of a spring 22 and is also attached to a flexible copper leader 23 extending downwardly through the spring.

This spring is partially housed and received by a fiber or other insulating tube. 2l, 'whlch is attached to thespring adjacent the lower end of the tube 21 and thespring 22, as clearly shown in the lower portion of Figure 7. The tube24 draws the rod l3 downwardly thus aiding in the separation of the severed portion of the fusible section, such action of the spring assistin in any expulsion action that takes place at this time. Obviously the spring and rod do not interfere with the expulsion action of the fuse structure under considerable overload, but rather assist in the adequate separation of the severed portion of the fusible section.

v By means of this construction a very largegap is obtained, and consequently there is no leakage that takes place after the fuse. has blown. This v avoids the heretofore serious defect in certain types of fuses due to leaking of the current between relatively closely positioned severed sections. of the fusible portion of the link. This leaking, as is well known, frequently destroys the acts as the substantially rigid member 'corresponding roughly to the rod l3 previously described. The lower end of the spring 22, the leader 23 and the tube 24 are attached by means of a relatively strong copper leader 25 to the lower contact 3. r r

The operation of this fuse is substantially the same as that previously described. Upon blowing of the fuse, the spring insures adequate separation-of the severed portion of the fusible section and the rigid tube projects partially from the lower end of the insulating cartridge or tube I.

Ifhe fusible section 2| may be of the same or of a'diiferent type from that previously described.

In 'the form of the invention shown in Figure. 8, a relatively rigid rod 26 is attached to the lower leader 21, and intermediate the ends of the rod 25 a helical spring 28 is secured. A flexible cop- In view of its per leader 2! extends-from theupper end of the rod 26 to the lower end of the fusible section.

This fusible section may be of the type previously described, or may consist of either low fus- I ible alloy wire, or nickel-silver wire, the nickelsilver wire being preferred. As shown in Figure 8,

1 a single strand of wire has been shown for illus-.

tratlon.

At this point it is to be distinctly understood that any suitable type of fusible section may be employed. For example, in any forms of the invention any one of the several forms of fusible sections may be used in place of those specifically shown, or any other type of fusible section may be used.

It is to be again noted that the fuse cartridge or tube may be of any suitable form, the simplest form having been chosen merely for the sake of simplicity of illustration. In actual construction, it is frequently desirable to surround the inner tube with an outer porcelain tube, although this specific phase of the construction forms no portion of the invention.

Further it is to be distinctly understood that while Figurel shows the preferred form of construction, that nevertheless other types of fusible sections may be employed. or other types of construction conforming to the general spirit of the invention herein discussed. a

It will be seen that a novel form of expulsion fuse and fuse link therefor has been disclosed,

in which adequate separation of the severed portion of the fusible section is insured, irrespective of whether the overload is small or large, and it will be noted further that the action of the spring in no way interferes with the expulsion action of the fuse, but materially assists in the separation of the severed portion of the'fusible element.

From actual tests conducted with this apparatus, it has been found that in by far the larger number of cases no damage is done to any portion of the fuse structure when the fuse blows, other than the fusible section, and that the parts may be used over and over, the fusiblesection alone being renewed.

It will be seen further that a very simple type of construction has been provided by this invention which is eminently practical, which may be cheaply made, and which is easy to renew and care for. 7

Although thi invention has been described in considerable detail, it'is to be understood that such description is intendedas illustrative rather than limiting, as the invention may be variously,

' tion, and a h lical pring coaxial with said relatively rigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths.

2. A fuse link comprising a fusible section, a relatively rigid section, a flexible conducting section and a helical spring guided by said relatively rigid section and telescopically associated with said relatively rigid section.

3. A fuse comprising a non-extensible tube having an open lower end and having contacts adjacent each end; a fuse link carried within said tube and joining said contacts, said link comprising a fusible section, a relatively rigidelongated section, and a fiexible' section, and a spring secured to said relatively rigid section, said rela- 'the open end of said tube when said fusible portion is ruptured.

5. An expulsion fuse comprising a tube having an open lower end and having an upper contact and a lower contact; a fuse link in said tube and joining said contacts, said link having a fusible portion and a relatively rigid portion; and a spring for separating the severed portions of said fusible portion when said fuse blows, said rela-' tively rigid portion of said link projecting downwardly from the open end of said tube when said fusible portion is ruptured, and means for preventing said relatively rigid portion from passing completely from said tube.

6. An expulsion fuse comprising a tube having upper and lower contacts, a fuse link joining said contacts and having an upper fusible portion located in the upper portion of said tube, a spring for aiding, during the expulsion action of said fuse, in the separation of the severed portions of said link, and means for preventing the expulsion of the entire length of the spring from said tube.

7. A fuse link comprising a fusible section, a relatively rigid section, a flexible conducting section, and a helical spring coaxialwith said relatively rigid section, said spring and said relatively rigid section being coextensive for, at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube and said helical spring having one end thereof anchored at one end of said tube.

8. A fuse link comprising a fusible section, a relatively rigid section, a flexible conducting section, and a helical spring coaxial with said relativelyrigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube and said helical spring being wholly carried by the link and with its lowermost end secured adjacent the lower end of the insulating tube.

9. A fuse link comprising a fusible section, a relatively rigid section, a flexible. conducting section, and a hellcal spring coaxial with said relatively rigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube and said fusible section being in electrical connection at one end with a terminal adjacent one end of said tube and in electrical connection at its other end with said flexible section and with one end of said helical spring, said spring having its other end in electrical connection with said flexible conducting section adjacent the other end of said insulating tube, and arranged to bias a portion of the fusible section'away from said terminal.

10. A fuse link comprising a fusible section, a relatively rigid section. a flexible conducting section, and a helical spring coaxial with said relatively rigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube, and

said springinterconnecting said tube and said fusible section and placing the latter in tension. 11. A fuse link comprising a fusible section; a

- relatively rigidsection, a flexible conducting section, anda helical spring coaxial with said relatively rigid section, said spring and-said relatively rigidsection being coextensive for at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube and said flexible conducting section extending through said spring, and out of an end of said insulating tube.

12. A fuse link comprising a fusible section, a relatively rigid section, a flexible conducting section, and a helical spring coaxial with said relatively rigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube and said flexibl conducting section extending through said spring and out of an end of saidin sulating tube, the portion of said flexible conducting section inside said spring being slack, whereby when the link is inserted in an expulsion type fuse cartridge and upon a pull being applied to the flexible conducting section the force of said pull iy rigid section comprising an insulating tube and said flexible conducting section being in the form of a wire electrically connected at its upper end to said fusible section, a portion of said wire inside said tube between saidfusible section and the lower end of the tube being of a length greater than the distance bet'weensaid' fusible section and the lower end of the tube, and said spring being so arranged and connected with respect to said tube and wire'that when the link is inserted in-a standard expulsion type fuse cartridge and a pull is exerted on said conducting section in apf plying the link to'said cartridge-an end of the is initially applied to said fusible section only through saidspring.

13. A fuse link comprising a fusible section, a relatively'rigid section, a flexible conducting section, and a helical spring coaxial with said rela-,

tively rigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths, said relatively rigid section comprising a tube of such diameter and length as to be insertabie'within an expulsion fuse cartridge closed at one end and open at the other and having spaced external terminals to be electrically connected by said link.

14. A fuse'link comprising a fusible section, a relatively rigid section, a flexible conducting section, and a helical spring coaxialj-with said relatively rigid section, said spring and said relatively rigid section being coextensivev for-at least a portion of their respective lengths, said relatively rigid section comprising an insulating tube of such diameter and length as to' interrelate and support the fusible section' the flexible conducting section and the helical spring in a unitary inexpensive readily replaceable device adapted to be inserted into a standard expulsion type fuse cartridge for electrically connecting the termi-- nals of the fuse cartridge together, with the spring exerting a biasing force within the link whereby a quick separation of the parts of the fusible section will be obtained when said section is ruptureii by reason of a relatively small overload.

15. A fuse link comprising a fusible section, a relatively rigid section, a flexible conducting section, and a helical spring coaxial with said relatively rigid section, said'spring and said relatively rigid section being coextensive for at least; a portion of their respective lengths, said relatively rigid section comprising an insulating tube and said flexible conducting section extending through said spring and electrically connected at its upper end with said fusible section and having'its lower portion extending-out of thalower end ;of the tube. a

16. A fuse link comprising a fusible section, a relatively rigid section,ia flexible conducting section, and a helical'spring coaxial with said relatively rigid section, said spring and said relative- 7 spring may be pulled out of said insulating tube. 1.7. A fuse link comprising a fusible section, a relatively rigid section, a flexible conducting section, and ahelical spring coaxial with said relatively rigid section, said spring and said relatively rigid section being coextensive for at least a portion of their respective lengths, said relatively rigid section comprisingan insulating tube to guide the coils of said spring,'and said flexible conducting section also being coextensive with said spring and in electrical connection with said fusible section.

18. A fuse link comprising a fusible section, a-

relatively rigid section, a flexible conducting section, and a helical spring guided by said relative- 1y rigid section and telescopically associated with said relatively rigid section, said relatively rigid section comprising an insulating tube and said spring and flexible conducting section being in electrical connection with the. lower end of said fusible section, said flexible conducting section being secured to said spring for applying the tension of said spring to said fusible section.

19. A fuse link comprising a fusible section, a

relatively rigid section, a flexible conducting sec-'- tion, and a helical spring guided by said relative- 1y rigid section and telescopically associated with said relatively rigid section, said relatively rigid section comprising an insulating tube'and said spring and flexible conducting section being in electrical connection with the lower end of said fusible section and electrically in parallel with one another.

20. A fuse link comprising a' fusible section, a relatively rigid section, a flexible conducting section, and a helical springguided by said relativelyrigid section and telescopically associated with said relatively rigid section, said rigid section comprising an insulating tube of such diameter and length that said spring is guidable within and by said tube, and said spring being held unly rigid section being coextensive for at least a der tension between said tube and said fusible section.

21. The fuse link-of claim 1 further characterized by the-relatively rigid section being of a tubular formation and with said spring extending through a portion of the tubular section adjacent an end thereof for stressing the fusible section.

22. The-fuse link of claim 2 further characterized by the relatively rigid section being of a tubular formation and with said springdisposed in a portion of the tubular section adjacent an end thereof for stressing the fusible section with said fusible section operatively associated with an upper extremity of the rigid tubular section.

izedby the rigid section being of a tubular formation and by a DOrtion of the spring stressed between one extremity of the tubular formation and an extremity of the fusible section.

" 24. A renewable fuse link adapted to be dis- 23. The fuse link of claim 2 further characterposed substantially entirely within an expulsion" iuse cartridge closed at its upper end and open at its bottom end, having spaced terminals to be i electrically connected by. said link, said link com- 25. A renewable fuse link adaptedto be mounted as a unit in an expulsion fuse cartridge closed at its upper end' and open at its bottom end and having spaced terminals to be electrically connected by said link, said l.nk comprising a relatively fusible section, a relatively rigid tubular section cooperable with the fusible section in the holding of the same under stress, a flexible conducting section and a helical spring guided by said relatively rigid tubular section and telescopingly associated therewith: for placing the fusible section under stress.

ALWIN G. STEINli/IAYER. 

